The present invention relates to a cutting device with a heated cutting wire which can be brought into and out of contact with the material to be cut. The invention also relates to a process for cutting material employing the cutting device.
Before lamination carriers, such as printed circuit boards, multilayer laminations, metal plates or substrates with metal layers evaporated and/or glued on both sides, are laminated with a photoresist film, the latter is stretched free of folds on horizontally or vertically aligned suction plates of vacuum tables. The photoresist film is then cut to the desired size required to ensure that the film is laminated on the particular lamination carrier with perfect matching.
The laid-open European Patent Applications Nos. 40,842, 40,843 and 41,642 disclose laminating devices in which a substrate or a lamination carrier is laminated on both sides with a dry resist by the exertion of pressure. The dry resist for the particular side of the lamination carrier, for example, a printed circuit board, to be laminated, is drawn off a supply roll and fed to a pair of laminating rollers. The two dry resist films and the lamination carrier located between them are then passed through the nip of the rollers.
German Patent Application No. P 34 20 429.6 describes a cutting device for cutting dry resist films. The device incorporates a rotary knife, the height of which is adjustable and which can be moved over vacuum tables which are vertically arranged. As soon as the rotary knife has reached its predetermined height, it is moved transversely over the vacuum table in order to cut through the dry resist film stretched on the suction plate of the vacuum table. The rotary knife is arranged on a knife carrier mounted pivotally on guides which are displaceable along the vertical guide rods on both sides of the vacuum tables. A cross-member connects the two guides and is equipped with struts, to which is fastened a rail extending transversely relative to the photoresist film and having a cutting edge. The cross-member can be clamped in the desired position on the guide rods by means of a clamping piece. A gear intended for the knife drive and engaged with the rack is driven by a motor and is moved over the width of the photoresist film. The gear causes the rotary knife to rotate and moves it along the cutting edge of the rail, over the photoresist film, during the cutting operation. Cutting takes place mechanically so that the rotary knife always has to be ground sharp to prevent the photoresist film from splintering off along the cut edge, which occurs when the rotary knife is blunt. The movement of the rotary knife transversely over the photoresist during cutting is relatively slow in comparison with the cutting device which is also described in this German patent application and which operates with a heated cutting wire instead of a rotary knife. The latter cutting device is pivotal about a pivot axle which is actuated by a motor. The pivot axle is mounted in guides which can be fixed in a preselectable position along guide rods by a positioning device. A bearing arm is mounted on each of two bearing blocks resting on the pivot axle. The bearing arms are connected at their other ends to a carrier for the cutting wire. For the cutting operation, the carrier is pivoted by means of the motor in a circular path in the direction of the supporting rail for the photoresist film. The cutting wire, when it penetrates into the slot in the supporting rail, severs the photoresist film resting on the supporting rail. Because the cutting wire is positioned vertically, the problem arises that the preselected position of the cutting wire, which, for example, is fixed by means of a positioning device, only indirectly indicates the actual cutting point, and thus the dimensions of the cut-to-size photoresist film. The cutting wire does not execute a linear movement, but instead, an arcuate movement towards the photoresist film.